Is COD MW2 Worth It?

From a SP perspective, I like the campaign very much. Each mission seems tailored in a specific way and the overall vibe is good and realistic enough (I love the Amsterdam segment)
Although I feel like they made the campaign rather short, or atleast I would've liked it to be a little bit longer than it currently is.

Can't say anything about MP yet, but as I said, from a SP standpoint I think the game is worth it.

LE: As others pointed out around here, you should wait for a sale if you're only looking towards the SP experience as the campaign might not be worth 60-70 bucks.